en discovered, what had been done, whether there
was more that I could do. I kept thinking things over all the morning,
and half the afternoon. Then it suddenly struck me--there was one
thing--that I'd never done and that ought to have been done--I don't know
why I'd never thought of it till then--but I'd never had this photograph
out of the watch. And so I went back to the police-station and got the
watch and opened it, and--look there, Mr. Allerdyke!"

He had snapped open the case of the watch as he talked, and he now
detached the photograph and turning it over, laid the reverse side down
on the table by the postcard.

"Look at it!" he went on. "Do you see?--there's writing on it! You see
what it says? 'This is J.A. Burn this when made use of.' You see?
And--it's the same handwriting as that on this card, making the
appointment! Here, look at both for yourself--hold 'em closer to the
light. Mr. Allerdyke--that was all written by the same hand, or
I'm--no good!"

Allerdyke went close to the electric globe above his dressing-table, the
photograph in one hand, the postcard in the other. He looked searchingly
at both, brought them back, and laid them down again.

"No doubt of it, Chettle," he said. "No doubt of it! It doesn't need any
expert to be certain sure of that. The same, identical fist, without a
shadow of doubt. Well--what d'ye make of it? Here--have a drink."

He mixed a couple of drinks, pushed one glass to the detective, and took
the other himself.

"Egad!" he muttered, after drinking. "Things are getting--hottish,
anyway. As I say, what do you make of this? Of course, you've come to
some conclusion?"

"Yes," answered Chettle, taking up his glass and silently bowing his
acknowledgments. "I have! The only one I could come to. The man who sent
this photograph to Lydenberg, to help him to identify your cousin at
sight, is the man who afterwards lured Lydenberg into that part of Hull
High Street, and shot him dead. In plain words, the master shot his
man--when he'd done with him. Just as he poisoned the Frenchwoman--when
he'd done with her. Mr. Allerdyke, I'm more than ever convinced that
these two murders--Lydenberg's and the French maid's--were the work of
one hand."

"Likely!" assented Allerdyke. "It's getting to look like it. But--whose?
That's the problem, Chettle. Well, I've done a bit since I got back this
afternoon. You've had something to tell me--now I've something to tell
you. I've found out w